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build_stepped_shaft

Build a stepped cylindrical shaft with multiple diameters. Specify diameters and lengths for each step, and optionally a sweep angle less than 360 for a partial sector.

Instructions

Flecha escalonada — build a stepped (multi-diameter) cylindrical shaft in one call. Standard turned-part workflow for autoparts: flechas de transmisión, bujes con escalones, poleas, ejes de salida.

Junior workflow: "una flecha de Ø10×20, luego Ø20×30, luego Ø15×15". Composes: create_reference_axis(front, top) -> X axis through origin create_sketch("front") -> profile in XY plane create_line × N -> stepped half-silhouette revolve_sketch(axis_name) -> boss-revolve

Args: diameters_mm: List of step diameters in mm. One per step. Must be 1..20 entries, all > 0. v1 has no taper — each step is a pure cylinder of constant diameter. lengths_mm: List of step lengths in mm. Same length as diameters_mm. All > 0. angle_deg: Sweep angle in (0, 360]. Default 360 = full revolution. Partial angles produce a sector (useful for cams or half-housings). merge: True (default) merges with adjacent solid material. False keeps the shaft as a separate body (multi-body modeling).

Returns dict: name, type, dimensions: Standard Feature info from revolve_sketch (type='boss_revolve', D1=angle_deg). axis_name: The "Eje{N}" reference axis created. Reusable in circular_pattern or further revolve calls. step_count, total_length_mm, max_diameter_mm: Computed metadata for the LLM to verify against intent.

Caveat (v1 orientation): the shaft always grows along the +X world axis from the origin, sketched on the Front plane. To orient differently, use revolve_sketch directly with a custom axis + sketch plane.

Caveat (transitions): each step is a square shoulder (no fillet/chamfer between steps). Post-process with fillet/chamfer on the resulting edges if smoother transitions are needed.

Caveat (no taper): each step is a pure cylinder. For tapered shafts (e.g. transmission shafts with conical sections), use revolve_sketch with a triangular profile section.

Example — 3-step pulley shaft: build_stepped_shaft( diameters_mm=[10, 20, 15], lengths_mm=[20, 30, 15], )

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
mergeNo
angle_degNo
lengths_mmYes
diameters_mmYes
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so description carries full burden. Describes internal composed workflow, return metadata, and parameter effects (merge, angle). Caveats about orientation and transitions add transparency. Could be more explicit about safety (additive vs destructive), but acceptable.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Well-structured with summary, workflow, args, returns, caveats, and example. Front-loaded with purpose. Every sentence adds value; no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 4 parameters, no output schema, and no annotations, the description covers all necessary aspects: argument constraints, return values, caveats for orientation, transitions, and tapering. Includes an example for clarity. Complete for agent selection and invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema provides no parameter descriptions (0% coverage). Description compensates by explaining each parameter: diameters and lengths constraints (1-20, >0, same length), angle_deg default and use for sectors, merge behavior. Adds meaning beyond schema types.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states the tool creates a stepped multi-diameter shaft in one call, with examples and distinction from primitive sketch tools. The title and description align with the name.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use guidance via junior workflow example and caveats that tell when alternative tools (revolve_sketch) should be used. Also lists limitations (square shoulders, no taper, fixed orientation).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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